The present invention relates to spine surgery and in particular relates to a vertebral fixation plate system and a method for its implantation and use in fusing vertebrae to one another.
It has long been known that one way to alleviate pain in patients who have suffered degeneration of spinal discs, so-called ruptured discs, is to remove the failed disc and replace it with an intervertebral support which can form a support for bone growth to fuse together the adjacent vertebrae. The conventional procedure for fusion of adjacent vertebrae involves insertion of a bone graft or an interbody fusion device between the vertebrae, together with implantation of a supporting plate by screwing the plate to each of the involved vertebrae to immobilize the vertebrae with respect to each other while the bones become fused together.
Until recently, it has not been considered too important a factor that there is a significant amount of x-ray exposure involved in the way spinal fusion has been performed. Recently, however, the importance of minimizing x-ray exposure, both for a patient and for medical personnel involved in such procedures, has been better appreciated. It is also an important objective in performing spinal fusion procedures to minimize the invasiveness and resulting trauma to the patient from the surgery itself, both by use of smaller incisions and by reducing the amount of time required to perform a procedure properly.
Conventional practice in implantation of vertebral fixation plates, at least in cervical spine fusion procedures, has been to expose the defective cervical disc to be removed, replace it with a bone graft or other interbody fusion device, place a vertebral fixation plate across the space between the vertebrae that are to be fused, in a position selected by the surgeon, and then, in some cases, secure the plate by installation of temporary fixation pins. Typically, a radiographic image is obtained to determine whether the plate is in a satisfactory location, and, if necessary, the location of the plate may be adjusted, but it is desired to minimize the amount of radiation to which a patient and attending physicians are exposed, and so if an image shows the plate not to be located precisely where desired, adjustment may be made without subsequent x-ray images being taken to evaluate the adjustment before the plate is permanently fastened to the involved vertebrae. The plate is then secured to the vertebrae utilizing suitable screws, but there is no common way except for experience to quickly establish an initial optimum position for the vertebral fixation plate.
To fasten the plate to the involved vertebrae, the surgeon may manually hold the plate in the finally determined position while using a drill guide and drill to bore and tap holes in the vertebrae to receive screws to fasten the plate. Alternatively, self-tapping screws may be used once a bore has been made, or self-drilling screws may be utilized, but the position of the plate on the vertebrae, once chosen, is typically maintained manually by the surgeon, with the possible use of temporary fixation pins.
As a result, plates are often implanted in serviceable but less than optimal positions on patients' spinal vertebrae. Thereafter, when a medical care provider studies an x-ray photograph of the affected portion of the patient's spine, if the plate is not aligned completely parallel with the spine, or is located off-center, there may be some serious concern, even if the less-than-perfect location of the plate is completely inconsequential as to its function in securing the vertebrae as they heal in a fused manner.
What is desired, then, is a spinal fixation plate system and a manner of installing it so as to enable a surgeon to perform a spinal fusion procedure in a minimally invasive manner, in a minimum amount of time, and yet to place the plate in the optimum location with respect to the vertebrae being fused.